Camille Freitag

Respiration from coarse woody debris as affected by moisture and saprotroph functional diversity in Western Oregon

Abstract Decomposing coarse woody debris (CWD) is a conspicuous and important component of forest ecosystems. Seasonal temperature and precipitation patterns influence heterotroph activity, which determines the rate of CWD decomposition. We tested the hypothesis that moisture content and heterotroph community composition influence carbon flux in freshly-cut Douglas fir (Pseudotsuga menziesii) logs. To evaluate the effects of physical penetration of bark and wood and transmission of basidiomycete compared with ascomycete fungi by insects, 360 experimental logs were assigned to five replicate sites, each with 12 heterotroph×moisture treatment combinations in 1995. Half of the logs in each heterotroph treatment received normal rainfall and half were placed individually under elevated clear plastic tents to reduce water inputs. Respiration was measured every 1–3 months. In 1996 and 1997 a different log representing each treatment combination was harvested from each replicate and analyzed for the presence of inoculated and colonizing fungi. Logs inoculated with decay fungi had higher respiration than uninoculated logs but this effect only approached significance (P=0.08) during the first season. Respiration was significantly higher in sheltered than in exposed logs. Our results indicate that respiration and wood decomposition rates may be depressed by high moisture content in the wet forests of the coastal Pacific Northwest.

Wood/plastic ratio: Effect on performance of borate biocides against a brown rot fungus

Abstract The effect of wood/plastic ratio and the presence of a boron compound on resistance to biodegradation of wood plastic composites (WPCs) by the brown rot fungus Gloeophyllum trabeum was investigated in a soil block exposure. Weight losses of all WPCs were generally lower than those of solid wood, even when only the wood component of the WPC was used in calculating weight loss. Higher wood content was associated with greater weight losses, suggesting that the plastic encapsulated wood at lower wood levels. Borates markedly reduced weight losses at all wood/plastic ratios. Weight losses tended to be slightly lower with a Na/Ca borate than with similar levels of zinc borate. Mechanical properties did not correlate well with weight losses under the conditions evaluated, but these effects may have been masked by moisture sorption. The causes and implications of these differences are discussed.

Effect of moisture and fungal exposure on the mechanical properties of hem-fir plywood

Hem-fir plywood were exposed to two brown rot fungi,Gloeophyllum trabeum andPostia placenta, and one white rot fungus,Trametes versicolor, to investigate the effect of fungal decay on mechanical properties of plywood. Results showed that modulus of rupture (MOR) and modulus of elasticity (MOE) of hem-fir plywood declined significantly by inoculating fungi, and weight loss of sample had a modest decrease. The fungi also made a greater effect on MOR than on MOE. Of three fungi,Postia placenta caused a most significant weight loss, andGloeophyllum trabeum resulted in a largest flexural properties loss. Substantial declines in MOR and MOE of hem-fir plywood were also observed when the plywood samples were stored under wet conditions over 15 weeks, even in, the absence of fungal attack.

Pentachlorphenol migration from treated wood exposed to simulated rainfall

Abstract The leaching of toxins from treated wood poses an, as yet, poorly quantified risk to both plant and animal life. In particular, the leaching of pentachlorophenol (PCP) into rainwater falling on treated wood over aquatic environments, such as bridges, is understudied. Computer models have been developed which predict the leaching of creosote from marine pilings. If data were available, similar models could be developed for PCP-treated bridges and the risk to waterways determined for various structural designs. Providing such data is the objective of this study, where the migration of PCP from treated wood under the influence of simulated rainfall was studied using a simulation system that delivered uniform rainfall rates over-treated wood. The runoff from the treated wood was captured and analyzed with high resolution gas chromatography combined with low resolution mass spectrometry. PCP migrated from treated wood into rainwater runoff at a fairly constant rate of approximately 0.15 g l-1 m-2. Small non-significant deviations were observed with rainfall rate, time, and temperature. We suggest that PCP migration rates from exposed treated wood can be modeled and thereby predict the migration of PCP from this source into the environment.

Long-term performance of fused borate rods for limiting internal decay in Douglas-fir utility poles

Abstract The ability of boron to diffuse from fused boron rods into surrounding wood was investigated on pentachlorophenol-treated Douglas-fir poles. Boron readily diffused into the wood surrounding the treatment holes and was present at protective levels in most poles within 1 year after application. The protected zone was generally confined to the treatment zone. Effective levels of boron were still present in this zone 15 years after treatment. Attempts to correlate the presence of decay fungi with residual boron levels indicated that these fungi were sometimes present in zones with boron at the lower threshold level of 0.5 kg m-3 boric acid equivalent (BAE), but most of the isolations could be explained by localized variations in distribution. Boron rods provided excellent long term protection against internal decay in Douglas-fir poles.

Capacity of Surface and Internal Groundline Treatments to Protect Untreated Douglas-Fir Posts

The capacity of groundline preservative pastes and fumigants to protect untreated Douglas-fir pole sections was evaluated over a 10-year period. Culturing of increment cores and closed-tube bioassays indicate that combinations of preservative pastes and fumigants applied at the groundline provide reasonable protection to the groundline zone, but do not completely protect the aboveground zone. In the absence of an oil-treated Shell, rapid fumigant loss occurs, which suggests that more frequent fumigant applications may be necessary to protect untreated wood.

Fumigant Treatment of Douglas-Fir Bridge Timbers

Abstract The residual protective effect of sodium n-methyldithiocarbamate (NaMDC) fumigant was investigated in Douglas-fir timbers in a bridge in western Oregon using fungal colonization and levels...

Performance of boron/fluoride rod for internal remedial treatment of Douglas-fir poles

Abstract The ability of boron and fluoride to migrate from a boron/fluoride rod was investigated over a 15 year period in Douglas-fir pole sections. Both components readily moved through the wood, but boron tended to be present at higher levels over the test reflecting the much higher boron content of the rods. The overall chemical levels suggested that higher dosages would be needed to more fully protect Douglas-fir poles.

Antifungal Activities of Four Cedar Foliage Oils to Wood Stain or Decay Fungi

Antifungal activities of essential oils have been extensively studied and these materials have the potential to replace synthetic biocides. In this study, the chemical composition of Leyland cypress (× Cupressocyparis leylandii), Monterey cypress (Cupressus macrocarpa), Western juniper (Juniperus occidentalis), and Port Orford cedar (Chamaecyparis lawsoniana) foliage oils were determined and their antifungal activities on wood were analyzed. GC-MS analysis showed that monoterpenoids represented more than 90 percent of the oils except Port Orford cedar oil, where monoterpenoids comprised only one third of the oil. Cedar oils were reduced the growth of selected mold fungi and were capable of some inhibition of decay fungi, but could not completely protect wood from stain or decay fungi.

Effect of Port Orford cedar cone extracts on mould and decay fungi

Abstract Steam distilled essential oil extracts from Port Orford cedar (Chamaecyparis lawsoniana) cones were evaluated for their ability to inhibit the growth of Aspergillus niger and a Trichoderma spp. as well as for their ability to inhibit fungal degradation of wood by Gloeophyllum trabeum, Postia placenta or Trametes versicolor. The extract limited growth by A. niger at the highest dilution level tested (5%) but failed to limit fungal degradation. The results suggest that cone extracts from this species have limited potential for producing bioactive compounds.